On 05/17/2013 11:19 AM, Sergey Naumov wrote:
But I've read in some sources (for example http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc) that seed list MUST include at least one seed from each DC and seed lists should be the same for each node.

Or it is fine if nodes from new DC have all seeds specified and nodes from old DCs have all seeds specified except seeds from new DC? In such interpretation rules have to be a bit modified:

I never have problems with adding new nodes and new DC having single seed per cluster in one old DC.

1. Nodes from the same DC should have identical seeds lists.
2. At least at one DC nodes MUST have in its seed lists seeds from all other DCs.


2013/5/17 Igor <i...@4friends.od.ua <mailto:i...@4friends.od.ua>>

    I see no reason to restart all nodes. You can continue to use seed
    from first DC - seed used for loading ring
    configuration(locations, token ranges, etc), not data.

    On 05/17/2013 10:34 AM, Sergey Naumov wrote:
    If I understand you correctly, GossipingPropertyFileSnitch is
    useful for manipulations with nodes within a single DC, but to
    add a new DC without having to restart every node in all DCs
    (because seeds are specified in cassandra.yaml and I need to
    restart a node after addition of a new seed from newly created
    DC), I anyway have to use cassandra-topology.properties and edit
    it on every node of a cluster.

    By the way, it it necessary to specify seeds if I use
    PropertyFileSnitch and there is info in
    cassandra-topology.properties about all nodes of a cluster?


    Yes, it is. Cassandra need seed(s), because topology properties
    have no info about token ranges.



    2013/5/17 aaron morton <aa...@thelastpickle.com
    <mailto:aa...@thelastpickle.com>>

        You should configure the seeds as recommended regardless of
        the snitch used.

        You need to update the yaml file to start using the
        GossipingPropertyFileSnitch but after that it reads the
        cassandra-rackdc.properties file to get information about the
        node. It reads uses the information in gossip to get
        information about the other nodes in the cluster.

        If there is no info in gossip about a remote node, because
        say it has not been upgraded, it will fall back to using
        cassandra-topology.properties.

        Hope that helps.

        -----------------
        Aaron Morton
        Freelance Cassandra Consultant
        New Zealand

        @aaronmorton
        http://www.thelastpickle.com

        On 15/05/2013, at 8:10 PM, Sergey Naumov <sknau...@gmail.com
        <mailto:sknau...@gmail.com>> wrote:

        > As far as I understand, GossipingPropertyFileSnitch
        supposed to provide more flexibility in nodes
        addition/removal. But what about addition of a DC? In
        datastax documentation
        (http://www.datastax.com/docs/1.2/operations/add_replace_nodes#add-dc)
        it is said that cassandra-topology.properties could be
        updated without restart for PropertyFileSnitch. But here
        (http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc)
        it it said, that "you MUST include at least one node from
        EACH data center. It is a best practice to have at more than
        one seed node per data center and the seed list should be the
        same for each node". At the first glance it seems that
        PropertyFileSnitch will get necessary info from
        cassandra-topology.properties, but for
        GossipingPropertyFileSnitch modification of cassandra.yaml
        and restart of all nodes in all DCs will be required. Could
        somebody clarify this topic?
        >
        > Thanks in advance,
        > Sergey Naumov.





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